Despite advances in device technology, approximately one-third of patients fail to respond adequately to cardiac resynchronization therapy (CRT) (see, e.g., Abraham W T, Fisher W G, Smith A L, et al.: Cardiac resynchronization in chronic heart failure. N Engl J Med 2002; 346:1845-1853). Left ventricular lead placement is an important determinant of response, and conventional lead placement strategy is directed towards targeting the lateral or posterolateral branches of the coronary venous system (see, e.g., Macias A, Gavira J J, Castaño S, et al.: Left ventricular pacing site in cardiac resynchronization therapy: Clinical follow-up and predictors of failed lateral implant. Eur J Heart Fail 2008; 10:421-427; Wilton S B, Shibata M A, Sondergaard R, et al.: Relationship between left ventricular lead position using a simple radiographic classification scheme and long-term outcome with resynchronization therapy. J Interv Card Electrophysiol 2008; 23:219-227). Despite being a useful approach for positioning leads, a lack of response still exists in many patients.
Some data suggest that specifically targeting the region of maximal electrical delay could improve response to CRT (see, e.g., Singh J P, Fan D, Heist E K, et al.: Left ventricular lead electrical delay predicts response to cardiac resynchronization therapy. Heart Rhythm 2006; 3:1285-1292) while other data suggest that specifically targeting the region of maximal mechanical delay could improve response to CRT (see, e.g., Macias et al.; Becker M, Franke A, Breithard O A, et al.: Impact of left ventricular lead position on the efficacy of cardiac resynchronization therapy: a two-dimensional strain echocardiography study. Heart 2007; 93:1197-1203; Ansalone G, Giannantoni P, Ricci R, et al.: Doppler myocardial imaging to evaluate the effectiveness of pacing sites in patients receiving biventricular pacing. J Am Coll Cardiol 2002; 39:489-499; Murphy R T, Sigurdsson G, Mulamalla S, et al.: Tissue synchronization imaging and optimal left ventricular pacing site in cardiac resynchronization therapy. Am J Cardiol 2006; 97:1615-1621).
As described herein, various exemplary techniques acquire at least physiologic mechanical information and assess the information, for example, to enhance guidance of LV pacing site optimization during CRT implant. Various exemplary techniques may be applied to one or more types of therapy (e.g., cardiac pacing therapies, ablation therapies, sensing therapies, nerve stimulation therapies, etc.).